BOF, EOF, and Bookmark Properties Example (VJ++)

This example uses the BOF and EOF properties to display a message if a user tries to move past the first or last record of a Recordset. It uses the Bookmark property to let the user flag a record in a Recordset and return to it later.

// BeginBOFEOFJ
import com.ms.wfc.data.*;
import java.io.*;
import com.ms.com.*;

public class BOFEOFBookmark
{
   Variant varBookmark; 
   BufferedReader in = 
      new BufferedReader(new InputStreamReader(System.in));
   String line = null;

   // The main entry point for the application.
   
   public static void main (String[] args)
   {
      BOFEOFBookmark b1 = new BOFEOFBookmark ();
      b1.BOFX();
      b1.BOFX2();
      System.exit(0);
      try
      {
         b1.finalize();
      }
      catch(Throwable te)
      {
         System.out.println("Exception: " + te.getMessage());
      }
   }

   // The main entry point for the application.
   
   public void BOFX()
   {
      // Declarations.
      Recordset rstPublishers = null;
      String strCnn;
      String strMessage;
      int intCommand = 0;

      strCnn = "Provider='sqloledb';Data Source='MySqlServer';"
         + "Initial Catalog='Pubs';Integrated Security='SSPI';";
      try
      {
         // Open a recordset with data from Publishers table.
         rstPublishers = new Recordset();
         rstPublishers.setCursorType(AdoEnums.CursorType.STATIC );
         rstPublishers.setCursorLocation( 
            AdoEnums.CursorLocation.CLIENT);

         // Use client cursor to enable AbsolutePosition property.

         rstPublishers.open(new String(
            "SELECT pub_id,pub_name FROM Publishers ORDER BY pub_name"), 
            strCnn, AdoEnums.CursorType.STATIC , 
            AdoEnums.LockType.BATCHOPTIMISTIC, 
            AdoEnums.CommandType.TEXT );
         rstPublishers.moveFirst();

         //Display information about current record and get user input.
         while ( true)
         {
            strMessage = "\nPublisher :" + 
               rstPublishers.getField("pub_name").getString() + "\n"
               + " (Record " + rstPublishers.getAbsolutePosition() 
               + " of " + rstPublishers.getRecordCount() + ")" + "\n\n" 
               + "Enter command : " + "\n"
               + "[1 - next / 2 - previous /" + "\n" 
               + "3 - set bookmark / 4 - go to bookmark] / 5 - quit]" ;
            System.out.println (strMessage);
            line = in.readLine();
            //No entry exits loop.
            if (line.length() == 0)
               break;
            //convert string entry to int.
            intCommand = Integer.parseInt(line);
            //out of range entry exits loop.
            if ((intCommand < 1) || (intCommand > 4)) break ;

            //Call method based on user's validated selection.
            MoveAny(intCommand, rstPublishers);
         }
      }
      catch( AdoException ae )
      {
         // Notify user of any errors that result from ADO.

         // As passing a Recordset, check for null pointer first.
         if (rstPublishers != null)
         {
            PrintProviderError(rstPublishers.getActiveConnection());
         }
         else 
         {
            System.out.println("Exception: " + ae.getMessage());
         }
      }
      
      // This catch is required if input string cannot be converted to
      // Integer data type. "TCS[VSD]"

      catch ( java.lang.NumberFormatException ne)
      {
         System.out.println("\nException: Integer Input required." );
      }

      // System Read requires this catch.
      catch( java.io.IOException je )
      {
         PrintIOError(je);
      }      
      finally
      {
         // Cleanup objects before exit.   
         if (rstPublishers != null)
            if (rstPublishers.getState() == 1)
               rstPublishers.close();
      }
   }

   // MoveAny Function

   public void MoveAny(int intChoice, Recordset rsTemp)
   {
      // Move Forward or backword per selection from user,
      // trapping for BOF and EOF.
      try
      {
         switch(intChoice)
         {
            case 1:   // Equals char of 1.
               rsTemp.moveNext();
               if (rsTemp.getEOF())
               {
                  System.out.println (
                     "\nMoving past the last record \nTry again." );
                  rsTemp.moveLast();
               }
               break;
            case 2:   // Equals char of 2.
               rsTemp.movePrevious();
               if (rsTemp.getBOF())
               {
                  System.out.println (
                     "\nMoving past the first record \nTry again." );
                  rsTemp.moveFirst();
               }
               break;
            case 3:   // Equals char of 3.
               // Store the bookmark of the current record.
               varBookmark = (Variant)rsTemp.getBookmark();
               break;
            case 4:   // Equals char of 4.
               // Go to the record indicated by the stored bookmark.
               if (varBookmark == null)
                  System.out.println ("\nNo bookmark set!");
               else
                  rsTemp.setBookmark((Object)varBookmark);
               break;
            default:
               break;
         }
      }
      catch( AdoException ae )
      {
         // Notify user of any errors that result from ADO.

         // As passing a Recordset, check for null pointer first.
         if (rsTemp != null)
         {
            PrintProviderError(rsTemp.getActiveConnection());
         }
         else
         {
            System.out.println("Exception: " + ae.getMessage());
         }
      }
   }

   // PrintProviderError Function

   static void PrintProviderError( Connection Cnn1 )
   {
      // Print Provider errors from Connection object.
      // ErrItem is an item object in the Connections Errors collection.
      com.ms.wfc.data.Error  ErrItem = null;
      long nCount = 0;
      int  i      = 0;

      nCount = Cnn1.getErrors().getCount();

      // If there are any errors in the collection, print them.
      if( nCount > 0);
      {
         // Collection ranges from 0 to nCount - 1
         for (i = 0; i< nCount; i++)
         {
            ErrItem = Cnn1.getErrors().getItem(i);
            System.out.println("\t Error number: " + ErrItem.getNumber()
               + "\t" + ErrItem.getDescription() );
         }
      }

   }

   //.PrintIOError Function
   
   static void PrintIOError( java.io.IOException je)
   {
      System.out.println("Error \n");
      System.out.println("\tSource = " + je.getClass() + "\n");
      System.out.println("\tDescription = " + je.getMessage() + "\n");
   }

   ////////////////////////////////////////////
   //            BOFX2() Function.           // 
   ////////////////////////////////////////////  
   
   public void BOFX2()
   {
      Recordset rs = null ;
      
      try
      {
         // Declarations.
         rs = new Recordset();
         Variant[] arrbmk = new Variant[11];
         rs.setCursorLocation( AdoEnums.CursorLocation.CLIENT);
            String strCnn = "Provider='sqloledb';Data Source='MySqlServer';"
            + "Initial Catalog='Pubs';Integrated Security='SSPI';";
         rs.setActiveConnection (strCnn);
         // Open recorset with data from authors table.
         rs.open((new  String("SELECT * FROM authors")),strCnn,AdoEnums.CursorType.STATIC ,AdoEnums.LockType.BATCHOPTIMISTIC,AdoEnums.CommandType.TEXT );
         System.out.println ("\nNumber of records before filtering : " + rs.getRecordCount() );
         int ii = 0;
         
         // Create array of bookmarks.
         while (rs.getEOF() != true && ii < 11)
         {
            arrbmk[ii] = (Variant)rs.getBookmark();
            ii++;
            rs.move (2);
         }
         
         // set Filter to recordset.
         Variant bmk=new Variant();
         bmk.putVariantArray(arrbmk);
         rs.setFilter(bmk);
         System.out.println ("\nNumber of records after filtering : " + rs.getRecordCount() );
      
         // Dislay the records after filtering.
         rs.moveFirst();
         while (!rs.getEOF())
         {
            System.out.println ("\t" +rs.getAbsolutePosition() + "  " +rs.getField("au_lname").getString());
            rs.moveNext();
         }
         rs.close();
         System.out.println ("\n\nPress <Enter> key to continue.");
         in.readLine();
         
      }
      catch( AdoException ae )
      {
         // Notify user of any errors that result from ADO.
         
         // As passing a Recordset, check for null pointer first.
         if (rs != null)
         {
            PrintProviderError(rs.getActiveConnection());
            System.out.println("Exception: " + ae.getMessage());
         }
         else 
         {
            System.out.println("Exception: " + ae.getMessage());
         }
      }
      // System Read requires this catch.
      catch( java.io.IOException je )
      {
         PrintIOError(je);
      }
   }
}


// EndBOFEOFJ

See Also

BOF, EOF Properties | Bookmark Property | Recordset Object